The present invention relates to an electronic camera and, more particularly, to an electronic camera capable of preventing deterioration of the picture quality due to a rise of the temperature of an image sensing element, and at the same time allowing the internal structure of the apparatus to be flexibly made compact.
In an electronic camera, heat is generated from portions consuming electric energy, such as an image sensing element for photoelectrical conversion, e.g., CCD, and a printed circuit board. Especially, the image sensing element generates a large amount of heat, which becomes more prominent, as the pixel density of the image sensing element is increased. However, as various kinds of members are closely mounted in the electronic camera, the effect of convection currents of air can be hardly expected. As a result, the temperature of the image sensing element, which is disposed deep in the electronic camera, tends to rise.
A rise of the temperature of the image sensing element increases the noise of the image sensing element, thereby causing deterioration of the picture quality. In particular, where the image sensing element has a high pixel density, a rise of the temperature of the image sensing element is a big problem, because such an image sensing element is required to have a high picture quality.
To solve these problems, there is a technique known in that a back plate supporting an image sensing element is used as a heat-radiating plate. Furthermore, for example, as a prior art to solve the same problems, Jpn. Pat. Appln. KOKAI Publication No. 7-154658 discloses a video camera in which a CCD is attached to an apparatus casing by an attaching member made of a heat-conducting material, so that heat generated by the CCD is radiated from the apparatus casing. Jpn. Pat. Appln. KOKAI Publication No. 9-65348 discloses a solid image sensing apparatus in which a Peltier cooling element is disposed behind a solid image sensing element. Jpn. Pat. Appln. KOKAI Publication No. 11-341321 discloses an image sensing apparatus in which an attaching member that supports an image sensing element and is made of a heat-conducting material is elastically brought into contact with an apparatus casing, so that heat generated by the image sensing element is radiated from the apparatus casing.
A heat-radiating plate (i.e., a back plate) that supports an image sensing element has a small thermal capacity, and thus provides a small heat-radiating effect. Where such a heat-radiating plate is extended to release heat to an apparatus casing, the layout of members in the apparatus is greatly restricted. If the heat of an image sensing element cannot be efficiently released, the temperature of the image sensing element rises, thereby deteriorating the picture quality. On the other hand, if the internal structure of the apparatus cannot be flexibly made compact, it is not difficult to satisfy demands on an electronic camera in recent years, for higher compactness, improved productivity, and lower price. That is, the conventional structure in which a back plate that supports an image sensing element is substantially extended to release the heat of the image sensing element to an apparatus casing still has antinomic problems: improving the picture quality and making the apparatus compact.